WHARTON, W.Va. — Two miners who were killed on the job Monday night worked in a coalfield that had so many safety problems federal officials deemed it a “pattern violator,” a rare designation reserved for the industry’s worst offenders.

Brody Mine No. 1 was one of only three mines last year to earn the label that regulators have put greater emphasis on since the 2010 Upper Big Branch explosion killed 29 miners about 10 miles away.

The designation subjects the mine to greater scrutiny from regulators, and it’s the strongest tool the Mine Safety and Health Administration has, said Kevin Stricklin, the agency’s administrator of coal mine safety and health.

“We just do not have the ability or authority to shut a mine just because it has so many violations,” Stricklin told The Associated Press on Tuesday.

Brody No. 1 is owned by a subsidiary of St. Louis-based Patriot Coal, which in its annual report last December blamed the problems on a previous owner and said it was “vigorously contesting” the designation.

The company said the workers were killed during a severe coal burst, where high-speed coal is shot at anyone in the way. The burst occurred as they were doing retreat mining, a risky method that involves yanking supporting pillars of coal from inside the mine and letting the roof collapse as miners and equipment work their way out.

“Preliminarily, it looks like it was a rock outburst from the wall of the mine, which basically inundated the entries with coal and debris,” said Stricklin. “That’s what caused the two fatalities.”

In August 2007, six miners doing retreat mining at Utah’s Crandall Canyon died in a collapse and 10 days later, three rescue workers were killed in another cave-in.

In October, Brody No. 1 was one of three coal mines added to a Pattern of Violations list for repeatedly breaking federal health and safety regulations over the previous year. It was cited for 253 serious violations.

The designation is for operations that pose the greatest threat to workers’ lives. It also meant that if a federal inspector were to find another significant violation, an order would be issued to withdraw miners from a specific area, effectively ceasing operations until the problem is corrected there.

But from April 1, 2013, to March 31 of this year, the mine was cited for 192 safety violations, including 33 for high or reckless disregard for miners’ health and safety.

It wasn’t immediately clear whether any of the violations could have had anything to do with a coal burst.

Since January, six accidents have occurred at Brody No. 1, including one in which a miner’s finger was caught in machinery and a portion had to be amputated, according to online federal records.

Stricklin said that since October, the company was slapped with 69 violations that required at least partial closure of the mine each time.

The Mine Safety and Health Administration has taken several steps to improve its enforcement of safety regulations after the Upper Big Branch explosion, the worst U.S. coal mining disaster in 40 years. Among them: impact inspections of problem mines, such as Brody No. 1, and “Rules to Live By.”